JP3358237B2 - Hologram element and focus detection mechanism using the same - Google Patents
Hologram element and focus detection mechanism using the sameInfo
- Publication number
- JP3358237B2 JP3358237B2 JP13866293A JP13866293A JP3358237B2 JP 3358237 B2 JP3358237 B2 JP 3358237B2 JP 13866293 A JP13866293 A JP 13866293A JP 13866293 A JP13866293 A JP 13866293A JP 3358237 B2 JP3358237 B2 JP 3358237B2
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- hologram element
- light
- correction term
- constant
- target surface
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- Diffracting Gratings Or Hologram Optical Elements (AREA)
- Optical Head (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光学式測定装置や光記
憶装置の光ヘッドなどに用いて好適なホログラム素子お
よびこれを用いた合焦検出機構に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram element suitable for use in an optical measuring device or an optical head of an optical storage device, and a focus detection mechanism using the same.
【０００２】[0002]
【従来の技術】光ヘッドなどにおいて、ホログラム素子
を搭載したものが最近特に注目されており、いろいろな
方式が開発されている。しかしながら、ホログラム素子
は決して万能というわけではなく、物理的な原理に係わ
る数多くの制約事項が存在し、これらを把握した上で、
適切な光学設計をしなければならない。2. Description of the Related Art Optical heads and the like equipped with a hologram element have recently received special attention, and various systems have been developed. However, hologram elements are by no means versatile, and there are many restrictions related to physical principles.
Appropriate optical design must be made.
【０００３】このような中で、発明者らは、特開平４−
２１２７４２号公報や特願平３−２９３３２９号出願な
どに記述しているように、ホログラム素子を用いて発生
した非点収斂光束を、光ヘッドの合焦検出に用いること
を提案している。Under such circumstances, the inventors have disclosed Japanese Patent Laid-Open No.
As described in Japanese Patent Application No. 212742 and Japanese Patent Application No. 3-293329, it has been proposed to use an astigmatic light beam generated by using a hologram element for focus detection of an optical head.
【０００４】これらは、図６に示すようにホログラム素
子１によって、焦点変化に伴って互いに相補的に非点変
化する±１次回折光２，３を発生し、この光束を適切な
形状の光電変換素子４，５で検出して、２つの検出出力
を差動させることで合焦検出するものであり、構成によ
っては光ディスク装置に必要な各種信号をも全て出力さ
せることができる。[0006] As shown in FIG. 6, the hologram element 1 generates ± first-order diffracted lights 2 and 3 whose astigmatism changes complementarily with a change in focal point, and converts this light beam into an appropriately shaped photoelectric conversion. Focusing is detected by detecting the signals with the elements 4 and 5 and making the two detection outputs differential. Depending on the configuration, all the various signals necessary for the optical disk device can be output.
【０００５】一般に、このような合成されたホログラム
素子では、パターンを適切に設計することが必要である
が、実際の用途には、例えばこのようなホログラム素子
の一種に分類できる回折格子やフレネルゾーンプレート
のように、その平行光束中でのパターン形状が高々二次
曲線に沿うような、簡単なものが主となっている。In general, it is necessary to appropriately design a pattern in such a synthesized hologram element. In actual use, for example, a diffraction grating or a Fresnel zone which can be classified as a kind of such a hologram element is used. Like a plate, a simple one in which the pattern shape in the parallel light beam follows a quadratic curve at most is mainly used.
【０００６】上記のホログラム素子１でも、平行光路中
に置かれる場合では、直線や双曲線が好ましいことが発
明者らによって開示されている。It is disclosed by the inventors that the above-mentioned hologram element 1 is preferably a straight line or a hyperbola when placed in a parallel optical path.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、光ディ
スク装置のヘッドなどでは、光学系全体を小型化すべ
く、途中に平行光路を介さないいわゆる有限光学系が求
められることが多い。このような場合、ホログラム素子
は収束／発散する球面波中に配置せざるを得ず、平行光
路中でのパターン形状をそのまま適用したのでは、所望
の回折光束を得ることができない。特に、上記の例のよ
うに、ホログラム素子の複数の回折光を利用する場合に
は、これらは互いに従属関係にあり、パターン形状を任
意に定めても両者をバランス良く最適化するには困難が
伴う。However, in order to reduce the size of the entire optical system, a so-called finite optical system that does not pass through a parallel optical path is often required for the head of an optical disk device or the like. In such a case, the hologram element must be arranged in a converging / diverging spherical wave, and a desired diffracted light beam cannot be obtained if the pattern shape in the parallel optical path is applied as it is. In particular, when a plurality of diffracted lights of the hologram element are used as in the above example, they are dependent on each other, and it is difficult to optimize both in a well-balanced manner even if the pattern shape is arbitrarily determined. Accompany.
【０００８】本発明の目的は、上述の問題点を解消し、
収束または発散光路中で複数の回折光を利用する場合で
も、パターン形状に適切な補正を加えることにより、補
正前の平行光路中での光束に近似した所望の回折光束が
得られるホログラム素子およびこれを用いた合焦検出機
構を提供することにある。An object of the present invention is to solve the above-mentioned problems,
Even when a plurality of diffracted lights are used in a convergent or divergent light path, a hologram element that can obtain a desired diffracted light beam similar to a light beam in a parallel light path before correction by applying an appropriate correction to the pattern shape, and To provide a focus detection mechanism using the same.
【０００９】[0009]
【課題を解決するための手段】上記の目的を達成するた
めに、本発明に係るホログラム素子においては、 １． 収束または発散光路中に配置されたホログラム素
子において、前記ホログラム素子上の直交座標系(x,y)
による高々２次の原関数Ｆ(x,y)に、座標変数ｙに関す
る奇関数である高々３次の補正項Ｍ(x,y)を加えた曲線 Ｆ(x,y)＋Ｍ(x,y)＝一定 に沿ってパターンを形成してなり、前記直交座標系のｙ
軸に沿って回折光を分離することを特徴とする。In order to achieve the above object, a hologram element according to the present invention comprises: In a hologram element arranged in a convergent or divergent light path, a rectangular coordinate system (x, y) on the hologram element
A curve F (x, y) + M (x, y) obtained by adding at most a third-order correction term M (x, y), which is an odd function related to the coordinate variable y, to a second-order original function F (x, y) based on ) = Constant, and a pattern is formed along the rectangular coordinate system.
It is characterized by separating diffracted light along an axis.
【００１０】そして必要に応じ、 ２． 上記１において、前記補正項Ｍ(x,y)は、定数ａ
を用いて Ｃ(x,y)＝ａ・（ｘ2ｙ＋ｙ3） に従うコマ収差補正項Ｃ(x,y)を含む。[0010] If necessary, In the above 1, the correction term M (x, y) is a constant a
And includes a coma aberration correction term C (x, y) according to C (x, y) = a · (x 2 y + y 3 ).
【００１１】３． 上記１ないし２において、前記原関
数Ｆ(x,y)は双曲線関数とする。3. In the above 1 and 2, the original function F (x, y) is a hyperbolic function.
【００１２】また、本発明に係る合焦検出機構において
は、 ４． 合焦目標面からの反射光を収斂させる検出光学系
と、直交座標系(x,y)による高々２次の原関数Ｆ(x,y)
に、座標変数ｙに関する奇関数である高々３次の補正項
Ｍ(x,y)を加えた曲線「Ｆ(x,y)＋Ｍ(x,y)＝一定」に沿
ってパターンを形成してなり、前記直交座標系のｙ軸に
沿って回折光を分離する、前記検出光学系の収束光路中
に配置されたホログラム素子と、前記検出光学系に関し
て前記合焦目標面と概ね共役な同一の検出平面上に配置
された一対の光検出手段とを備え、前記光検出手段によ
り一対の前記非点収斂光束を検出し、一対の前記光検出
手段の出力を比較することにより、前記合焦目標面への
合焦を検出することを特徴とする。Further, in the focus detection mechanism according to the present invention, A detection optical system for converging the reflected light from the focusing target surface, and a quadratic original function F (x, y) based on a rectangular coordinate system (x, y)
And a pattern is formed along a curve “F (x, y) + M (x, y) = constant” in which a third-order correction term M (x, y) which is an odd function related to the coordinate variable y is added. A hologram element arranged in a converging optical path of the detection optical system, which separates diffracted light along the y-axis of the orthogonal coordinate system, and the same hologram element that is substantially conjugate to the focusing target surface with respect to the detection optical system. A pair of light detecting means arranged on a detection plane, wherein the light detecting means detects the pair of non-point convergent light fluxes, and compares the outputs of the pair of light detecting means to obtain the focusing target. It is characterized in that focusing on a surface is detected.
【００１３】[0013]
【作用】上記の構成によれば、補正項Ｍ(x,y)は回折分
離方向であるｙに関して奇関数である。正負の回折光束
に対してホログラム素子が付与する波面の関数は、互い
に正負が逆転することになるが、奇関数の場合は正負の
逆転はｙ軸の向きの反転と同じ意味を持つ。すなわち、
正負次の回折光に補正の効果が等しく現れ、ｙに関する
偶数次の項が含まれないので、バランスの良い補正が実
現される。According to the above arrangement, the correction term M (x, y) is an odd function with respect to the diffraction separation direction y. The function of the wavefront imparted by the hologram element to the positive and negative diffracted light beams is inverted in the positive and negative directions. In the case of an odd function, the positive and negative inversions have the same meaning as the inversion of the y-axis direction. That is,
The effect of the correction appears equally in the positive and negative order diffracted lights, and an even-order term for y is not included, so that a well-balanced correction is realized.
【００１４】[0014]
【実施例】本発明を図１ないし図５に図示の実施例に基
づいて詳細に説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS.
【００１５】（実施例１） 図１および図２は、本発明の効果が最も分かりやすい形
で現れる単純回折格子での実施例を示す。図１におい
て、収束レンズ１１により収束された光路中に、本発明
のホログラム素子１２が配置されており、正負の一次光
１３，１４を発生している。ここで、ホログラム素子１
２は、回折分離方向にｙ軸をとった直交座標(x,y)につ
いて、適当な定数αによる原関数 Ｆ(x,y)＝α・ｙ と、ｙに関しての奇関数である補正項Ｍ(x,y)により、 Ｆ(x,y)＋Ｍ(x,y)＝一定 に沿ってパターンを形成してなっている。補正がないと
きの原関数Ｆ(x,y)から得られるパターンは Ｆ(x,y)＝α・ｙ＝一定 すなわちｙ軸に直交する直線であるから、原関数だけか
らなる場合は、ホログラム素子は単純な回折格子であ
り、入射光から正負の一次光を発生し、平行入射光の場
合に限っては、これらは収差のない平行光となる。(Embodiment 1) FIGS. 1 and 2 show an embodiment using a simple diffraction grating in which the effects of the present invention appear most clearly. In FIG. 1, a hologram element 12 according to the present invention is arranged in an optical path converged by a converging lens 11 and generates primary and negative primary lights 13 and 14. Here, the hologram element 1
2 is an original function F (x, y) = α · y with an appropriate constant α for the orthogonal coordinates (x, y) taking the y-axis in the diffraction separation direction, and a correction term M which is an odd function with respect to y. By (x, y), a pattern is formed along F (x, y) + M (x, y) = constant. The pattern obtained from the original function F (x, y) without correction is F (x, y) = α · y = constant, that is, a straight line orthogonal to the y-axis. The element is a simple diffraction grating, which generates positive and negative primary lights from incident light, and becomes parallel light without aberration only in the case of parallel incident light.
【００１６】しかしながら、収束球面波が入射したとき
には、正負の一次光は図２(a)のようにいわゆるコマ収
差を含んだスポットを結び、補正のない単純格子では、
収差のない回折光は得られない。However, when a convergent spherical wave is incident, the primary light of positive and negative forms a spot including so-called coma as shown in FIG. 2 (a).
Diffraction light without aberration cannot be obtained.
【００１７】これに対し、本発明のように奇関数の補正
項Ｍ(x,y)を加えた場合は、図２(b)のように例えば＋１
次回折光１３に対して、光線Ｌ１の位置を方向Ａ１に移
動させるような補正が行われたとすると、対応する−１
次回折光１４の光線Ｌ２も方向Ａ２に対称的に移動し、
正負の回折光に同じ補正が行われる。On the other hand, when an odd function correction term M (x, y) is added as in the present invention, for example, as shown in FIG.
Assuming that the next diffracted light 13 is corrected so as to move the position of the light ray L1 in the direction A1, the corresponding -1
The light ray L2 of the second-order diffracted light 14 also moves symmetrically in the direction A2,
The same correction is made for positive and negative diffracted light.
【００１８】特に、発明者らが行ったところによれば、
適当な定数βを用いて、 Ｍ(x,y)＝β・（ｘ2ｙ＋ｙ3） と定めたとき、上記の収束球面波の回折光は、図２(c)
のようにコマ収差補正が行われて、良好な回折光スポッ
ト１５，１６となる。In particular, according to what the inventors have done,
When M (x, y) = β · (x 2 y + y 3 ) is determined by using an appropriate constant β, the diffracted light of the convergent spherical wave is shown in FIG.
As described above, coma aberration correction is performed, and good diffracted light spots 15 and 16 are obtained.
【００１９】なお、仮に偶関数の補正項Ｎ(x,y)では、
図２(d)のように＋１次回折光１３に対して光線Ｌ１の
位置を方向Ａ１に移動させるような補正を行おうとする
と、対応する−１次回折光１４の光線Ｌ２は方向Ａ３に
移動してしまうので、両回折光を同時に適正化すること
はできない。したがって、例えば非点収差に代表される
ような偶関数の収差は、本発明によっても複数の回折光
から同時に無くすことはできない。It is assumed that the correction term N (x, y) of the even function is
As shown in FIG. 2D, when an attempt is made to correct the position of the light beam L1 in the direction A1 with respect to the + 1st-order diffracted light 13, the corresponding light beam L2 of the -1st-order diffracted light 14 moves in the direction A3. Therefore, the two diffracted lights cannot be optimized at the same time. Therefore, even function aberrations, such as astigmatism, cannot be eliminated simultaneously from a plurality of diffracted lights by the present invention.
【００２０】以上のように本実施例によれば、収束光を
回折によって複数の光に分離する際に、収差発生を最小
限に抑さえることができるので、例えばホログラム素子
による光の分離を積極的に利用する光ヘッド等で、その
利点を最大限に活用することができる様になる。As described above, according to the present embodiment, when the convergent light is separated into a plurality of lights by diffraction, the occurrence of aberration can be suppressed to a minimum. The advantage can be maximized with an optical head or the like that is used for the purpose.
【００２１】（実施例２）図３ないし図５は、本発明に
係る合焦検出機構の実施例を示している。図３におい
て、合焦操作の対象となる投射光２１は、合焦目標面２
２により反射されており、反射光２３は、レンズ２４を
介して収束され、ホログラム素子２５に入射している。(Embodiment 2) FIGS. 3 to 5 show an embodiment of a focus detection mechanism according to the present invention. In FIG. 3, a projection light 21 to be subjected to a focusing operation is a focusing target surface 2.
2, the reflected light 23 is converged via a lens 24 and is incident on a hologram element 25.
【００２２】ホログラム素子２５では、反射光２３によ
って±１次回折光２６，２７が発生され、二つの回折光
２６，２７は同一の検出平面２８に置かれた光検出手段
２９，３０で受光されている。In the hologram element 25, ± first-order diffracted lights 26 and 27 are generated by the reflected light 23, and the two diffracted lights 26 and 27 are received by light detecting means 29 and 30 placed on the same detecting plane 28. I have.
【００２３】ここで、±１次回折光２６，２７は、互い
に直交する非点収差を付与されており、しかも目標面２
２への合焦時には、これらの最小錯乱円が前記の光検出
手段２９，３０上に来るように配置されている。Here, the ± 1st-order diffracted lights 26 and 27 are given astigmatism orthogonal to each other, and the target surface 2
At the time of focusing on 2, the circles of least confusion are arranged so as to come on the light detecting means 29, 30.
【００２４】このような構成を実現するために、ホログ
ラム素子２５では、回折方向をｙ軸に取った直交座標
(x,y)において、双曲線方程式に従う原関数Ｆ(x,y)と、
ｙに関する奇関数の補正項Ｍ(x,y)とによって Ｆ(x,y)＋Ｍ(x,y)＝一定 で表される曲線群に沿った光変調パターンが設けられて
いる。すなわち、原関数Ｆ(x,y)によって上記の二つの
非点収差が発生され、補正項Ｍ(x,y)は不要な収差を抑
えるためのものである。これらにより±１次回折光２
６，２７は互いに直交方位の非点収差を検出平面２８を
挟んで生成されている。In order to realize such a configuration, the hologram element 25 uses orthogonal coordinates with the diffraction direction taken on the y-axis.
In (x, y), the original function F (x, y) according to the hyperbolic equation,
A light modulation pattern is provided along a curve group represented by F (x, y) + M (x, y) = constant with the correction term M (x, y) of the odd function relating to y. That is, the above two astigmatisms are generated by the original function F (x, y), and the correction term M (x, y) is for suppressing unnecessary aberrations. With these, ± 1st order diffracted light 2
6 and 27, astigmatisms in orthogonal directions are generated with the detection plane 28 interposed therebetween.
【００２５】ここで、前記の光検出手段２９，３０は水
平方向に長尺な形状とされており、二つの非点回折光２
６，２７の前後移動に伴うスポットの変形を検出するこ
とができる。すなわち、合焦目標面２２がレンズ２４に
近い場合には、反射光２３は全体として後方Ａ４に移動
するので、例えば＋１次回折光２６の検出平面２８上で
のスポットは横長となって光検出手段２９の出力は増加
し、−１次回折光２７のスポットは縦長となって光検出
手段３０の出力は減少する。一方、合焦目標面２２がレ
ンズ２４から遠い場合には、反射光２３は全体として前
方Ａ５に移動するので、＋１次回折光２６のスポットは
縦長となって光検出手段２９の出力は減少し、−１次回
折光２７のスポットは横長となって光検出手段３０の出
力は増加する。Here, the light detecting means 29 and 30 have a long shape in the horizontal direction.
It is possible to detect the deformation of the spot due to the forward and backward movement of 6, 27. That is, when the focusing target surface 22 is close to the lens 24, the reflected light 23 moves to the rear A4 as a whole, so that, for example, the spot of the + 1st-order diffracted light 26 on the detection plane 28 becomes horizontally long and the light detection means The output of the photodetector 30 decreases, and the output of the photodetector 30 decreases. On the other hand, when the focus target surface 22 is far from the lens 24, the reflected light 23 moves forward A5 as a whole, so that the spot of the + 1st-order diffracted light 26 becomes vertically long, and the output of the light detecting means 29 decreases. The spot of the -1st-order diffracted light 27 becomes horizontally long, and the output of the light detecting means 30 increases.
【００２６】従って、光検出手段２９，３０の出力差を
零と比較することにより、実質的に投射光２１の目標面
２２への合焦を検出することができる。すなわち、光検
出手段２９，３０どうしの出力差を縦軸にとり、合焦目
標面２２の位置を横軸にとると、図４のような合焦エラ
ー信号が得られ、横軸との交差位置が合焦点であること
がわかる。光学式測定装置や光記憶装置に適用する際
は、この合焦エラー信号と制御目標値の差信号を求め、
必要に応じて適当な位相補償を加えてアクチュエータの
駆動信号とし、レンズと目標面の距離を調節すればよ
い。Therefore, by comparing the output difference between the light detecting means 29 and 30 with zero, it is possible to substantially detect the focus of the projection light 21 on the target surface 22. That is, when the output difference between the light detecting means 29 and 30 is taken on the vertical axis and the position of the focusing target plane 22 is taken on the horizontal axis, a focusing error signal as shown in FIG. 4 is obtained, and the intersection position with the horizontal axis is obtained. Is the focal point. When applied to an optical measuring device or an optical storage device, a difference signal between this focusing error signal and a control target value is obtained,
The distance between the lens and the target plane may be adjusted by adding an appropriate phase compensation as necessary to generate a drive signal for the actuator.
【００２７】このような合焦検出機構では、スポットの
形状を検出することで合焦を検知しており、収差の発生
は正確な検知に支障を来たすことが多いが、本発明では
補正項Ｍ(x,y)によって不要な収差の発生が最小限に抑
さえられるので、良好な合焦検出を行うことができる。In such a focus detection mechanism, focus is detected by detecting the shape of a spot, and occurrence of aberration often hinders accurate detection. Since (x, y) minimizes the occurrence of unnecessary aberrations, good focus detection can be performed.
【００２８】すなわち、たとえば適正な非点収斂光束で
は理想的には焦線がいずれも直線状であるべきが、原関
数Ｆ(x,y)のみでは、図５(a)のように不要な収差が焦線
の形状に歪みを生じる。これに対して本実施例のように
補正項Ｍ(x,y)を加えると、不要な収差の発生は抑さえ
られることになる。特に上記のように適当な比例定数β
によって Ｍ(x,y)＝β・（ｘ2ｙ＋ｙ3） とした場合にはコマ収差補正ができ、図５(b)のような
理想的な形状に近い焦線が得られることが確かめられ
る。That is, for example, in a proper astigmatic light beam, all the focal lines should ideally be linear, but only the original function F (x, y) is unnecessary as shown in FIG. Aberration causes distortion of the shape of the focal line. On the other hand, when the correction term M (x, y) is added as in the present embodiment, the occurrence of unnecessary aberrations is suppressed. In particular, the appropriate proportional constant β
Therefore, when M (x, y) = β · (x 2 y + y 3 ), it is confirmed that coma aberration can be corrected and a focal line close to an ideal shape as shown in FIG. 5B can be obtained. .
【００２９】なお、本実施例では双曲線群に沿った光変
調パターンのホログラム素子２５を用い、同一の検出平
面２８上で検出する場合について説明したが、前述した
収差発生の問題は、いかなるホログラム素子でも本質的
に内包している問題であるから、上述の実施例以外の場
合にも適用できる。たとえば、ホログラム素子２５の光
変調パターンを直線化して、検出平面２８を段違いに設
けるような場合でも適用可能であり、同様な効果を得る
ことができる。In the present embodiment, the case where the hologram element 25 having a light modulation pattern along the hyperbolic group is used and the detection is performed on the same detection plane 28 has been described. However, since this is an inherent problem, it can be applied to cases other than the above-described embodiment. For example, the present invention can be applied to a case where the light modulation pattern of the hologram element 25 is linearized and the detection plane 28 is provided at a different level, and the same effect can be obtained.
【００３０】また、本実施例では±１次回折光を使用す
る場合について説明したが、回折次数はこれに限るもの
ではなく、±２次回折光を使用する場合などでも同様に
実施できる。In this embodiment, the case where the ± 1st-order diffracted light is used has been described. However, the diffraction order is not limited to this, and the same can be applied to the case where the ± 2nd-order diffracted light is used.
【００３１】[0031]
【発明の効果】以上説明したように、本発明に係るホロ
グラム素子および合焦検出機構においては、収束光を回
折によって複数の光に分離する際に、収差発生を最小限
に抑さえることができるので、ホログラム素子による光
の分離を最大限に活用することができる。特に光ヘッド
などの合焦検出機構などに用いれば、スポットの収差は
最小限に抑さえられ、信頼性が高くバランスの良い、良
好な合焦検出が可能であり、小型で高性能な関連装置を
提供できる。As described above, in the hologram element and the focus detection mechanism according to the present invention, when the convergent light is separated into a plurality of lights by diffraction, it is possible to minimize the occurrence of aberration. Therefore, the light separation by the hologram element can be maximized. In particular, when used in a focus detection mechanism such as an optical head, spot aberrations are suppressed to a minimum, and reliable, well-balanced, and good focus detection is possible. Can be provided.
【図１】 本発明の一実施例に係るホログラム素子によ
る回折の説明図。FIG. 1 is an explanatory diagram of diffraction by a hologram element according to one embodiment of the present invention.
【図２】 本発明の一実施例に係るホログラム素子の動
作を示す説明図。FIG. 2 is an explanatory diagram showing an operation of the hologram element according to one embodiment of the present invention.
【図３】 本発明の他の実施例に係る合焦検出機構の構
成を示す概略斜視図。FIG. 3 is a schematic perspective view showing a configuration of a focus detection mechanism according to another embodiment of the present invention.
【図４】 本発明の他の実施例に係る合焦検出機構によ
る出力信号の説明図。FIG. 4 is an explanatory diagram of an output signal by a focus detection mechanism according to another embodiment of the present invention.
【図５】 本発明の他の実施例に係る合焦検出機構にお
ける光スポットの説明図。FIG. 5 is an explanatory diagram of a light spot in a focus detection mechanism according to another embodiment of the present invention.
【図６】 従来の合焦検出機構の構成を示す概略斜視
図。FIG. 6 is a schematic perspective view showing a configuration of a conventional focus detection mechanism.
１１ 収束レンズ １２ ホログラム素子 １３，１４ ±１次回折光 ２２ 合焦目標面 ２５ ホログラム素子 ２６，２７ ±１次回折光 ２８ 検出平面 ２９，３０ 光検出手段 DESCRIPTION OF SYMBOLS 11 Convergent lens 12 Hologram element 13, 14 ± 1st-order diffracted light 22 Focus target surface 25 Hologram element 26, 27 ± 1st-order diffracted light 28 Detection plane 29, 30 Light detection means
フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G02B 7/28 - 7/40 G02B 5/32 Continuation of the front page (58) Field surveyed (Int.Cl. 7 , DB name) G02B 7/ 28-7/40 G02B 5/32
Claims (4)
グラム素子において、前記ホログラム素子上の直交座標
系(x,y)による高々２次の原関数Ｆ(x,y)に、座標変数ｙ
に関する奇関数である高々３次の補正項Ｍ(x,y)を加え
た曲線 Ｆ(x,y)＋Ｍ(x,y)＝一定 に沿ってパターンを形成してなり、前記直交座標系のｙ
軸に沿って回折光を分離することを特徴とするホログラ
ム素子。1. A hologram element disposed in a convergent or divergent optical path, wherein a coordinate variable y is assigned to a quadratic original function F (x, y) based on a rectangular coordinate system (x, y) on the hologram element.
A pattern is formed along a curve F (x, y) + M (x, y) = constant to which at most a third-order correction term M (x, y) which is an odd function related to the orthogonal coordinate system y
A hologram element for separating diffracted light along an axis.
請求項１に記載のホログラム素子。2. The correction term M (x, y) includes a coma aberration correction term C (x, y) according to C (x, y) = a · (x 2 y + y 3 ) using a constant a. The hologram element according to claim 1, wherein:
ことを特徴とする請求項１または請求項２に記載のホロ
グラム素子。3. The hologram element according to claim 1, wherein the original function F (x, y) is a hyperbolic function.
出光学系と、 直交座標系(x,y)による高々２次の原関数Ｆ(x,y)に、座
標変数ｙに関する奇関数である高々３次の補正項Ｍ(x,
y)を加えた曲線「Ｆ(x,y)＋Ｍ(x,y)＝一定」に沿ってパ
ターンを形成してなり、前記直交座標系のｙ軸に沿って
回折光を分離する、前記検出光学系の収束光路中に配置
されたホログラム素子と、 前記検出光学系に関して前記合焦目標面と概ね共役な同
一の検出平面上に配置された一対の光検出手段とを備
え、前記光検出手段により一対の前記非点収斂光束を検
出し、一対の前記光検出手段の出力を比較することによ
り、前記合焦目標面への合焦を検出することを特徴とす
る合焦検出機構。4. A detection optical system for converging reflected light from a focusing target surface; and an at most quadratic original function F (x, y) based on an orthogonal coordinate system (x, y), and an odd function related to a coordinate variable y. At most a third-order correction term M (x,
forming a pattern along a curve “F (x, y) + M (x, y) = constant” to which y) is added, and separating the diffracted light along the y-axis of the rectangular coordinate system. A hologram element arranged in a converging optical path of an optical system, and a pair of light detection means arranged on the same detection plane which is substantially conjugate with the focusing target surface with respect to the detection optical system, wherein the light detection means A focus detection mechanism for detecting a focus on the focusing target surface by detecting a pair of the astigmatic light beams and comparing outputs of the pair of light detection means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13866293A JP3358237B2 (en) | 1993-06-10 | 1993-06-10 | Hologram element and focus detection mechanism using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13866293A JP3358237B2 (en) | 1993-06-10 | 1993-06-10 | Hologram element and focus detection mechanism using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06347689A JPH06347689A (en) | 1994-12-22 |
| JP3358237B2 true JP3358237B2 (en) | 2002-12-16 |
Family
ID=15227210
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13866293A Expired - Lifetime JP3358237B2 (en) | 1993-06-10 | 1993-06-10 | Hologram element and focus detection mechanism using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3358237B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3653923B2 (en) * | 1997-03-19 | 2005-06-02 | ソニー株式会社 | Recording / reproducing apparatus and method |
| JP3362768B2 (en) * | 1998-02-19 | 2003-01-07 | 株式会社ケンウッド | Optical pickup device |
| US7215605B2 (en) * | 2001-06-29 | 2007-05-08 | Koninklijke Philips Electronics N.V. | Optical scanning device with coma correction for improved focus tracking signal |
-
1993
- 1993-06-10 JP JP13866293A patent/JP3358237B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06347689A (en) | 1994-12-22 |
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